Medical probe with consistent action

ABSTRACT

A probe for intermittent contacting a patient body with a predetermined speed and force. Initially, the probe is recessed inside the device which is brought in contact with the patient body, while keeping the probe from making a contact with the patient. On a command from an operator or control circuit, the probe is deployed moving toward the patient body surface with a substantially consistent force and rate of motion, thus making a contact in a consistent fashion.

This invention claims the benefit of the U.S. Provisional PatentApplication No. 60/727,938 filed Oct. 19, 2005.

FIELD OF INVENTION

This invention relates to medical probes. More particularly it relatesto probes of the intermittent thermometers for detecting temperaturefrom the surface of a patient.

BACKGROUND OF THE INVENTION

Medical information may be obtained either from the interior of a bodyor non-invasively from its exterior. Apart from non-contact devices, asensing probe is being brought in a physical contact with the biologicaltissue. Such a probe may incorporate some kind of a sensor. Examples ofthe sensors include a microphone, measuring gauge, light emitters anddetectors and a temperature transducer. In some applications, the probeis attached to the patient body on a continuous basis, while in otherapplications the probe shall be brought intermittently into a contactwith the biological tissue (skin, e.g.) to perform some kind of medicalprocedure, such as measurement or treatment. It may be important forvarious reasons (accuracy, consistency, rate of the sensor's response,etc.) to bring the probe in a contact with the patient body in aconsistent manner that is substantially independent of the operatortraining and operation, patient behavior and other uncontrollable orunpredictable factors. In other words, the probe shall move toward thepatient body with a relatively pre-defined speed 20 and come in acontact with a predictable force. One example that is given here by wayof a reference is a medical probe with an electromagnetic control taughtby Warming in the U.S. Pat. No. 4,209,021. An example of a need toproduce a consistent pressure by a probe is a body surface temperatureprobe of the U.S Patent Application Publication No. US-2005-0043631-A1.This probe may produce too mach of a variability if it is pressed to theskin with 25 a random force thus making an inconsistent thermal contactand modulating the subcutaneous blood perfusion. These factors, in turn,may affect the measured skin temperature. Controlling a rate of theprobe deployment toward the skin and the force of a contact is importantfor such a device.

It is therefore an object of the present invention to provide a meansfor making a fast and consistent contact between a medical probe and thepatient tissue.

Another goal of this invention is to find a way of the probe to bedeployed at the moment of forming of a contact between the skin and themedical device.

And another goal of this invention is to develop a method of anintermittent and consistent interaction between the medical probe andthe body surface.

SUMMARY OF THE INVENTION

To make a consistent contact between the probe and surface of a patientbody, initially, the sensing probe is recessed inside the device whichis brought in contact with the patient body, while keeping the probefrom making a contact with the patient. On a command from an operator orinternal controller, the probe is deployed and moves toward the patientbody surface with a substantially constant force and rate of motion,thus making a contact in a consistent fashion.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view of a medical device pressing against thepatient body.

FIG. 2 illustrates a cross-sectional view of a temperature probe.

FIG. 3 illustrates variable rates of a response of a temperature sensor.

FIG. 4 is a cross-sectional view of the probe of FIG. 1 in a standbymode.

FIG. 5 shows the probe of FIG. 4 with a fully deployed sensor.

FIG. 6 is a schematic of the first embodiment in a standby mode.

FIG. 7 is the schematic of FIG. 6 with a deployed sensor.

FIG. 8 is a schematic of a second embodiment in a stand-by mode.

FIG. 9 is the schematic of FIG. 8 with a deployed sensor.

FIG. 10 depicts a cross-sectional view of the third embodiment of thesensor in three positions: A-standby, B-trigger, and C-deployed.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 illustrates a handheld medical device 7 intended for touching aselected location on skin 1 of a patient's body. Device 7 mayincorporate display 6 and control pushbutton 5. The head 3 is brought ina direct contact with the patient. Pushbutton 5 may be actuated by thumb4. The device may be useful either for taking a measurement, forexample, measuring temperature, or for treatment, for example,delivering a medication. In either application, the probe hidden insidethe head 3 shall move to the skin 1 with a predetermined speed andforce.

An example of a contact temperature probe is shown in FIG. 2. Probe 9 isformed as a tube with a hollow interior. Its sensor 8 consists of a flator dome shaped metal plate 56 where temperature transducer 50 (forexample, a thermistor with the top-bottom terminations) is attached bysolder or conductive epoxy 54. Connecting wires 51 and 52 makeelectrical connections between an electronic circuit (not shown) to thetransducer 50 and plate 56 at the point 53. After the sensor 8 of theprobe 9 is brought in contacts with the patient, plate 56 touches theskin 1 and transfers heat from the skin to transducer 50. The rate of aheat transfer will depend on depth of the impression of plate 56 intothe skin 1. As shown in FIG. 3, the shape of the transducer's 50response may change depending on the force exerted by the sensor 8 anddepth of impression (curve 61 represents a result from a shallowerimpression than curve 60) and in a case when the signal processingrelies on that shape, accuracy may be compromised. A cause for suchinconsistency may be, for example, a different pressure exerted by ahand of an operator on device 7 when it is brought in coupling with thepatient (FIG. 1). To minimize the variability, this invention teaches away to deploy probe 9 toward the skin in a consistent manner that issubstantially independent on the operator's technique.

FIG. 4 illustrates the sensing head 3 and its interior in a standbystate. Probe 9 is recessed inside a cavity 62 of the sensing head 3.Sensor 8 may incorporate a temperature transducer or any other suitabledevice for measuring or treating a patient. Sensor 8 is positioned at adistal end of probe 9. The outer rim 10 of sensing head 3 may be broughtin contact with the patient skin. The rim 10 and the sensing head 3 forma guard around the probe 9. When the rim 10 initially touches the skin,sensor 8 is still not making a contact because it is hidden in a cavity62 inside the sensing head 3. Probe 9 is attached to a mechanism 14which, in turn, may be actuated by an electronic circuit (not shown) oralternatively mechanically by depressing pushbutton 5 or by way ofpressing rim 10 to the patient skin 1. Now turning to FIG. 5, noticethat pushbutton 5 is depressed in direction 12. This initiates operationof the mechanism 14. The mechanism is built and programmed to respond tothe pushbutton 5. Upon the pushbutton 5 is pressed, mechanism 14 quickly(within 100 ms or less, e.g.) deploys the probe 9 which moves indirection 13 potentially all the way up to its end position 11. If rim10 touches the patient skin, sensor 8 will not reach its end position 11but instead will be pressed against the skin with a specific force,defined by mechanism 14, and stopped.

There are several ways of designing the mechanism 14. One example wouldbe use of a solenoid whose core is coupled to probe 9. Other embodimentsmay include both the electrical and mechanical devices operating withlinear and/or rotating motions. The first example of a mechanicalembodiment with a manual actuation (FIG. 6) illustrates a mechanism thatdeploys probe 9 toward the end position 11. The figure shows themechanism in a “cocked” or stand-by state. Functionality of themechanism relies on spring 20 that when compressed and tilted, canremain in one of two stable positions where the first position is shownin FIG. 6. The spring 20 is coupled to both the probe 9 and button 12via a lever 16 which may rotate around pivot 19. Button 12 is forced tothe shown position by a return spring 17. The probe 9 is attached to thelever 16 and may move within the guide channel 15. The switch 22 islocated in the proximity of lever 16.

To deploy the probe 9, button 12 is moved in direction indicated byarrow 65. A bump 28 which is part of the button 12 engages with thelever 16 and moves it and subsequently the probe 9 leftward. This causesthe spring 20 to compress and tilt toward its unstable position aroundthe support 21. When the spring passes through the unstable position, itquickly snaps toward the second stable position shown in FIG. 7. Thissnap causes a fast rotation of the lever 16 in a direction indicated bythe arrow 26 and the probe 9 quickly moves in a direction 27 toward theend position 11. A rotation of the lever 16 actuates an optional switch22 that signals the electronic circuit of the probe deployment. As arule, the sensor 8 will not reach the end position 11 as it will bestopped by the skin surface (not shown) that will be pressed with apredetermined force defined by the properties of spring 20.

To return the mechanism back to its stand-by position of FIG. 6, thebutton 12 is released. This allows the return spring 17 to move button12 in a direction 24 and, subsequently slide probe 9 back and snapspring 20 across its unstable position to the first stable position.This re-cocks the mechanism and makes it ready for the next actuation.

The second embodiment of the probe deploying of the medical devicemechanism is shown in FIG. 8. It achieves the same result as above by adifferent method. Instead of releasing the probe toward the patientbody, it uses a moving guard 30 that surrounds and encloses the probe 9in a standby state. When actuated, the guard 30 is allowed to slide by asnap inside the frame 33 (which is a part of the device housing) andallow the probe 9 to protrude outside of the outer rim 32 of the guardso that the sensor 8 will press against the skin 1. The mechanism hasthe following key components shown in FIG. 8 in a standby state: theprobe 9 with the attached sensor 8, the spring 36, guard 30, frame 33with a finger 34 and optional switch 22. The guard 30 can move back andforth along axis 67. Initially, the guard 30 is locked in a standbyposition by the tooth 31 that is pressed to the release finger 34. Notethat the finger 34 is supported by a resilient neck 35 supported by theframe 33. In this example, switch 22 is normally open.

To operate, the outer rim 32 of the guard 30 is pressed against patientbody 1 by exerting force onto the frame 33 in a direction 66. This forcepresses tooth 31 against finger 34 resulting is development of stress inthe neck 35. So far, the probe 9 is hidden inside the guard 30 and itssensor 8 is not in contact with patient body 1. When force alongdirection 66 reaches a specific threshold value, the neck 35 snapsupwardly in direction 38 resulting in decoupling between the finger 34and tooth 31. The overwhelming force exerted onto the frame 33 of thedevice moves the entire device (the frame and housing with all internalcomponents) to the left as shown in FIG. 9. Since the finger 34 nolonger restricts movement of the guard 30, the latter slides torightward with respect to probe 9 and frame 33. This allows sensor 8 tomove beyond the outer rim 32 and come in a physical contact with patientskin 1. At that moment the guard 30 actuates switch 22 sensing a signalto the internal electronic circuit (not shown) manifesting the deviceactuation. When the sensor 8 presses against skin 1, the spring 36compresses, thus exerting a constant force on probe 9. Hence, a suddenand fast engagement of sensor 8 with a patient skin 1 creates aconsistent and predictable action that is generally independent on theoperator's technique. When the device is removed from the patient body,the mechanism must be re-cocked by sliding guard 30 leftward withrespect to the frame 33. This can be done by an additional spring (notshown) or manually.

A third embodiment of the medical device mechanism 14 that illustrateshow the probe deployment can be initiated by a contact between thepatient and the probe is illustrated in FIG. 10 which shows three stagesof the mechanism action. The first Stage A is the mechanism in a standbyposition. The medical device's housing 40 supports a moving guard 41,the probe 9, two springs 36 and 46, the trigger 44 and pusher 45. Theprobe 9 comprises a flange 42, shaft 43 and may incorporate at its outerend the sensor 8. A switch 22 is in a normally open state. Both theguard 41 and probe 9 can move along the axis 52 with respect to thehousing 40 and to each other. Note that the guard 41 and the probe 9 ina Stage A are engaged by forming a contact between the trigger 44 andflange 42. The guard 41 may encircle the probe 9, but alternatively itmay be located just in a close proximity to the probe 9. In most of themedical applications, they should be separated by a distance rangingfrom 1 to 10 mm.

When the skin 1 moves toward the outer rim 32 of the guard 41 (or viceversa—the guard moves toward the skin) in a direction 47 (FIG. 10-B) andthe skin pushes the guard 41 inside housing 40, the following happens.Both the guard 41 and probe 9 move rightward and thus compressing bothsprings 36 and 46. When the guard 41 moves, the trigger 44 (a part ofthe guard 41) drugs the probe 9 by the flange 42 (a part of the probe 9)in the same direction. The contacts of the switch 22 are being pressedby the shaft 43 thus making the switch to go a closed state. Thissignals the outside circuit (not shown) about the guard movement. Whenthe guard 41 moves far enough, that is to the point illustrated in FIG.10-B (a trigger Stage B), the pusher 45 (a part of the housing 40)engages with the trigger 44. This makes the trigger 44 to bend in thedirection illustrated by arrow 70 and decouple from the flange 42. Atthis moment, the probe 9 is released and the spring 36 pushes it towardthe skin 1 which brings the mechanism to the Stage C (a deployed stageof FIG. 10-C). Note that the spring 46 remains compressed by the guard41. In this stage, the probe 9 moves quickly in direction 48 and thesensor 8 (a part of the probe 9) plunges into the skin 1. Apredetermined force of impression of the sensor 8 into the skin 1 isassured by selection of the spring 36. At the moment when the probe 9starts moving toward the skin 1, the shaft 43 disengages the contacts ofthe switch 22 making the switch to revert back to an open state. Thissignals the external circuit of the probe deployment. After theappropriate medical procedure is complete and a physical contact betweenthe probe (or its sensor 8) and the patient body surface (skin 1) is nolonger required, the entire assembly is being moved away from the skin1. The spring 46 pushes the guard 41 outwardly back to its standbyposition and the mechanism re-cocks to its Stage A as in FIG. 10-A. Thedevice is now ready for repeating another action in the same manner asdescribed above.

While particular embodiments of the invention have been shown anddescribed, it will be obvious to those skilled in the art that changesand modifications may be made without departing from the invention inits broader aspects, and, therefore, the aim in the appended claims isto cover all such changes and modifications as fall within the truespirit and scope of the invention.

1. A medical device for contacting the patient body surface with apredetermined force, comprising: a housing, a guard supported by saidhousing and having an outer rim that comes in contact with the patientbody surface, a probe located near the guard and capable of motiontoward the patient body surface, an actuation mechanism for causingmotion of said probe.
 2. A medical device of claim 1 where said guard iscapable of motion with respect to said housing.
 3. A medical device ofclaim 1 further comprises a switch being actuated cooperatively withmotion of the probe.
 4. A medical device of claim 1 wherein said probeis capable of a motion from being in a first position of not contactingthe patient body surface to the second position of contacting thepatient body surface.
 5. A medical device of claim 1 wherein saidactuation mechanism comprises at least one spring.
 6. A method ofdeploying a medical probe to and engaging with the patient body surfaceconsisting of steps: positioning the probe in proximity of the guard,locating the probe in a first position that prevents the probe frommaking contact with the patient body surface, placing the guard on apatient body surface, moving the probe from said first position to thesecond position that allows the probe of making a contact with thepatient body surface.
 7. A method of deploying a medical probe of claim6 includes a further step of actuating a switch cooperatively with saidmoving of the probe.
 8. A method of deploying a medical probe of claim 6includes a further step of moving the probe to the first position afterthe probe was moved to the second position.
 9. A method of deploying amedical probe of claim 6 where moving of the probe from said firstposition to the second position is caused by said placing the guard on apatient body surface.